The present invention relates to rescue apparatus which includes as an essential element a rescue hoist designed for lowering or lifting persons or loads quickly and easily without a substantial effort on the part of the operator of the system. Unique components of this system in accordance with this continuation-in-part application include a haul-lock device movable between engaged and disengaged positions and which, when engaged, allows raising of a load as normal, but prevents descent even if the operator releases the control rope. Another unique component in accordance with this continuation-in-part application is a lock-off bar which allows the operator to lock the control rope, thereby securing the load and holding it without further effort on the part of the operator.
One conventional hoist device includes a rope drum supported on a bolt extending from a bracket by a free wheeling bearing or so-called roller friction clutch which permits the rope drum to freely rotate in one direction (counter clockwise, in the exemplary description) but which blocks rotation of the drum in the opposite direction (clockwise in the exemplary description). In a typical load lowering application, a rope is wound around the drum at least 1 1/2 and usually 2 1/2 (depending on rope diameter) turns so that a braking force is applied to the rope as it glides over the drum surface in the direction in which the drum rotation is blocked. In other words, the braking action results from the friction between the rope and the drum surface as the rope is wound onto and then off the non-rotating drum under the downward loading influence of the person (or object) being lowered. The load end of the rope is generally connected to one or more pulleys downstream of the hoist which provide a mechanical lifting advantage so that the operator need only exert a slight counterpull in order to control the descent of the person being lowered.
Hoisting devices of this type are disclosed in U.S. Pat. Nos. 3,703,218 and 3,807,696. In the latter patent, improved rope guide devices for the rope drum are disclosed. One arc-shaped guide is in the form of two laterally spaced bails arranged along a portion of the circumference of the rope drum and connected at the ends, forming a slot through which the rope may pass. The arrangement is such that one end of the rope, the so-called control end of the rope, may be guided onto the drum through the rope guide slot from various directions relative to the drum.
In applicant's parent application Ser. No. 07/928,009, the entirety of which is incorporated by reference, an improved hoist device is disclosed which contains several unique and advantageous features. For example, the cylindrical rope engaging surface of the rope drum is modified to include an upwardly and rearwardly directed taper in that portion of the drum closest to the hoist support bracket or backplate. The tapered roller drum prevents overlapping during raising even with no lower rope guide block installed on the backplate, and thereby greatly improves the efficiency of the system by the attendant reduction of friction. More specifically, the tapered surface of the drum forces the rope coming onto the drum during a lifting operation to slide off the taper towards the front of the drum, so that there is always space created for new rope to come onto the rear of the drum. This action is described in more detail in the '009 application.
The '009 parent application also describes an improved arcuate guide cage which prevents the rope from overlapping itself, and which prevents the rope from slipping between the guide and the drum.
The parent application also describes a unique centrifugal brake device for use with the hoist which constantly senses rope speed while lowering, and if an excessive speed is reached, grips the rope and prevents further descent.
This continuation-in-part application relates to two improved features which may be incorporated into a hoist device generally of the type disclosed in the '009 application. During a rescue operation involving lowering a rescue worker or a victim, it is often necessary to stop the lowering process and lock off the rope being used in order to check the system, check the victim, or change the system's rigging by, for example, converting it to a raising system. To achieve this end, this invention provides a T-shaped device located at the forward end of the arcuate rope guide (with the "cross bar" of the T extending transversely relative to the rope windings, i.e., parallel to the axis of rotation of the drum). This device permits the operator to lock the control end of the rope, thereby securing the load and holding it without further intervention on the part of the operator. Because this T-shaped bar is utilized in conjunction with a system as described in the '009 parent application, it experiences very little load, as the system itself by nature absorbs most of the load through the 1 1/2 to 2 1/2 wraps around the roller drum. Additional load is absorbed by the rope bending around the rope guide cage as described in the parent application. This T-shaped bar provides a very strong mechanism to lock off the rope as it emulates a tensionless anchor (a device used to anchor a rope, without decreasing its strength, by wrapping the rope several times around an essentially round object before tying the end off). In this way, the wraps of rope absorb much of the load before the tie-off is loaded.
The second improved feature in accordance with this continuation-in-part application is a manual haul-lock device which, when engaged, allows a load to be raised in normal operation, but prevents the load from being lowered. More specifically, when the lock is engaged, the load cannot descend even if the rope is let go, for example, between pulls, in the event of operator incapacitation, or while performing various rigging operations on the system. When the locking device is not engaged, the system operates as normal and raising and lowering may be performed in the usual manner.
This manual lock device includes a body portion mounted to the hoist backplate, a locking cam mounted for movement between operative (engaged) and inoperative (disengaged) positions, a torsion spring which normally biases the cam toward the rope, and a cam handle and spring loaded knob assembly which is used to move the cam between engaged and disengaged positions.
Both of the above mentioned devices will be described fully hereinbelow.
In its broader aspects, therefore, the present invention relates to a rescue system comprising a hoist including a backplate; a rope drum mounted on the backplate for rotation about an axis extending substantially perpendicular to the backplate, the rope drum having a rope engaging surface located between a pair of circular end flanges; a rope guide fixed to the backplate, the rope guide formed by a pair of elongated laterally spaced legs connected at opposite ends of the rope guide to define therebetween at least one rope slot, the rope guide having an arcuate shape conforming substantially to the circular end flanges of the rope drum; a generally T-shaped rope lock bar mounted on a forward end of the rope guide, the lock bar including a stem and a cross bar, the cross bar extending substantially parallel to an axis of rotation of the rope drum; and a lock mounted on the backplate for movement between engaged and disengaged positions, the lock including a cam which, when in the engaged position, permits movement of a rope in one direction but not in the opposite direction.
In another broad aspect, the invention relates to a rescue system comprising a hoist including a backplate; a rope drum mounted on the backplate, the rope drum capable of rotation in one direction only; the rope drum having a front and rear end flange on either side of a rope engaging surface; an arcuate rope guide including a thru slot fixed to the backplate and extending partially about the drum; and a cam lock assembly mounted to the backplate for rotation about an axis parallel to an axis of rotation of the rope drum, the cam lock assembly including a cam movable between an operative and inoperative position.
In still another aspect, the invention relates to a rescue system comprising a hoist including a backplate; a rope drum mounted on the backplate, the rope drum capable of rotation in one direction only; the rope drum having a front and rear end flanges on either side of a rope engaging surface; an arcuate rope guide including a thru slot fixed to the backplate and extending partially about the drum; a substantially T-shaped rope lock bar mounted on the rope guide and extending substantially transverse to the rope guide to permit a rope extending through the rope guide and partially about the drum to be wrapped about the lock bar.
Additional objects and advantages of the subject invention will become apparent from the detailed description which follows.